The FDA has knocked back a combination diabetes product based on Johnson & Johnson's canagliflozin and metformin because it wants more data on dosing. The regulator wants to make sure the canagliflozin component of the the twice-daily combination is comparable to the once-daily formulation of the drug, which was approved under the Invokana brand name earlier this year. Canagliflozin was the first compound in the brand new sodium glucose co-transporter 2 (SGLT2) inhibitor class to be approved for marketing in the US.